When performing surgery of the posterior segment of the eye (for example, vitreoretinal surgery), it is typically necessary to view the anatomy of the eye with an operating microscope. Generally, a standard operating microscope is able to view the structures of the anterior segment of the eye and the anterior portion of the posterior segment of the eye, but cannot provide viewing of the entire posterior segment. The reason for this is that the natural optics of the eye (normally consisting of the cornea and the crystalline lens) prevent the operating microscope from focusing on some structures in the posterior segment of the eye such as the retina.
Therefore, in order to focus the operating microscope on structures such as the retina, a vitrectomy lens with the appropriate optical properties is positioned between the eye and the microscope to compensate for the natural optics of the eye. Current vitrectomy lenses are reusable lenses made from optical glass, and in use, are usually held against the eye either with sutures, by hand, or with a silicone ring.
A drawback with glass vitrectomy lenses is that the lenses can be damaged during cleaning. A scratched or cloudy lens surface will reduce the optical quality of the lens. In addition, the methods of securing such lenses to the eye as described above can be unwieldy.
The present invention is directed to a self-adhering contact lens made of flexible material for adhering to cornea and scleral regions of the eye solely by capillary traction. As a result, separate means for holding the lens against the eye are not required. The lens is inexpensive enough to be disposable so that a new lens is used for each patient, thereby ensuring optimum optics. The lens includes a central lens portion optically shaped for viewing interior regions of the eye. The central lens portion has an interior concave surface with a radius of curvature R1 for contacting the cornea. An outer flange formed integrally with the central lens portion extends radially outwardly from the central lens portion. The outer flange has an interior concave surface extending from the interior concave surface of the central lens portion. The interior concave surface of the outer flange is designed to contact the sclera and has a radius of curvature R2 that is greater than the radius R1. The outer flange is shaped for deflecting relative to the central lens portion for conforming the interior concave surface of the outer flange to the sclera.
In preferred embodiments, the radius of curvature of the sclera is greater than the radius of curvature of the cornea. The radius of curvature R1 of the interior concave surface of the central lens portion approximates the radius of curvature of the cornea, and the radius of curvature R2 of the interior concave surface of the outer flange is less than the radius of curvature of the sclera. The outer flange has a thickness that is sufficiently less than the height of the central lens portion for enabling the outer flange to deflect relative to the central lens portion without substantially deforming the central lens portion.
The ratio of the height of the central lens portion to the thickness of the outer flange is preferably greater than about 7. The height of the central lens portion is preferably about 3.5 mm or greater and the thickness of the outer flange is in the range of 0.4 mm to 0.5 mm. In addition, the ratio of the outer diameter of the central lens portion to the outer diameter of the outer flange is preferably in the range of 0.83 to 0.88. The outer diameter of the central lens portion is preferably about 12 mm and the outer diameter of the outer flange is about 14 mm. Finally, the radii R2 and R1 preferably have a ratio R2/R1 of about 1.3.
In one preferred embodiment, the central lens portion has a flat exterior surface. In another preferred embodiment, the central lens portion has a concave exterior surface. Finally, in yet another preferred embodiment, the central lens portion has an angled exterior surface.